the salt of ammonia and hydrogen chloride. Its principal use is as an electrolyte in dry cells, and it is also extensively employed as a constituent of galvanizing, tinning, and soldering fluxes to remove oxide coatings from metals and thereby improve the adhesion of the solders. It is a component of many proprietary cold medicines and cough remedies. Ammonium chloride is a colourless, crystalline substance. It is highly soluble in water, readily forming a slightly acidic solution. It vaporizes without melting at 340° C (644° F) to form equal volumes of ammonia and hydrogen chloride. Ammonium chloride is yielded as a by-product in the ammonia-soda process for making sodium carbonate. It also is produced by reaction of ammonium sulfate and sodium chloride solutions.